It comes in two flavors: a cloud version that is delivered over the Internet, Office 365, and traditional software that runs on your PC, previously known as Office 15, now called Office 2013.

Both of these come in a few versions too. Office 365 University is for college students, faculty and staff. It will cost $79.99 for a four-year subscription, which Microsoft points out comes to $1.67 per month.

There's also the Office 365 Home Premium version, which is a single subscription meant to cover a family, or up to 5 users. Microsoft previously announced that it will cost about $100 a year, or$8.33 per month.

The downloadable-software versions also come in different versions: Office Home & Student 2013, Office Home & Business 2013, and Office Professional 2013. Those will cost $139.99, $219.99, and $399.99, respectively.

If you need Office for more than one computer in the house, it's obviously less expensive, at least at first, to buy the cloud version for $99 a year than to buy Office 2013 for multiple computers.

While it's true that you can also get a scaled-down version of Office for free via Microsoft's SkyDrive, these new versions of Office are set up to work with Windows 8 touch devices.

Google Apps, which competes most directly with Office 365, is free for schools. For businesses, it costs $50 per user per year.

Microsoft is releasing new business versions of Office 365 for Windows 8 on February 27.